Before anyone has a heart attack, let me explain. Patterns sweep out a trumpet shaped volume. Choke effect controls how quickly the pattern spreads radially; a plot of forward velocity vs sideways (radial) velocity rotated makes the trumpet shape. So, if you look at two patterns from widely differing chokes and shot at the distances where the patterns have equal diameter, you will find the patterns are indistinguishable.
Don, here's what Brister says about patterns in his chapter on "Choosing Chokes and Loads":
"The improved cylinder pattern, which exposes a higher percentage of its pellets to atmospheric resistance at the muzzle, spreads faster and in more direct ratio to distance. Gough Thomas explains this by suggesting that the full choke stays tight, then spreads out suddenly, something like the bell of a trumpet, while improved cylinder spreads out as a rather constant cone. My wife, after a particularly tiring day replacing test targets and tabulating data, suggested: 'Just tell them improved cylinder goes to hell gradually; full choke all at once.'"
Larry, with all due respect to Brister, I think he missed on some science. If fired in a vacuum, patterns would sweep out a cone as opposed to a trumpet when fired in air. The reason for the trumpet shape is that the pellets loose forward velocity (high velocity) much faster than sideways velocity (low velocity).
I don't think there's any disagreement to the more open chokes spreading faster. That's what they're designed to do. But there appears to be some disagreement on the trumpet shape issue--full having a narrow tube that rather suddenly transitions to a wide mouth, while IC has a wider tube with a more gradual transition to its mouth. Are you (and Jones) suggesting that the profile of IC and full patterns are actually the same in terms of how quickly they transition from the trumpet's tube to its mouth?
I do not accept that any part of the pattern spread changes "suddenly." Ballistics and aerodynamics don't work that way. The full choke is blooming over a longer distance/time than is the IC. Therefore, bell of the trumpet is foreshortened relative to the tube. The IC trumpet will remain proportional to the full at distance, assuming their pellets have similar rates of slowing.
DDA
